Polymeric acetal resins (polyacetals) are resistant to degradation in aqueous environments and are therefore useful in applications in which the polymer is in contact with water for extended periods of time. Polyacetals also have excellent physical and mechanical properties. This combination of properties makes polyacetals particularly useful in plumbing application, such as water faucets and showerheads.
A problem that is encountered with essentially all materials when used in plumbing fixtures is the accumulation of mineral deposits. This problem occurs with metals as well as plastics. The problem is especially noticeable in showerheads, where large volumes of water pass through small openings at elevated temperatures. The mineral build-up is generally more noticeable when "hard" water is used (i.e. water with a high mineral content) and is often a problem in rural areas which rely on wells for water. This mineral accumulation results in unsightly deposits, and in some instances, such as showerheads, the accumulated minerals can eventually interfere with the operation of the plumbing fixture. If a material can be found which resists the accumulation and adhesion of such mineral deposits, certain plumbing fixtures, such as showerheads, could be designed with a longer useful life.
Inorganic fillers are often included in polymeric acetals and other polymers to modify the physical properties according to the particular end use. However, it does not appear that practitioners in the art have recognized that certain inorganic fillers improve the resistance of specific polymers to the build-up and adhesion of mineral deposits.